The Effect of Different Vitrification Protocols on Cell Survival in Human Ovarian Tissue: A Pilot Study
Abstract BackgroundVitrification has superseded the slow freezing method for cryopreservation of oocytes, embryos, and sperm, but there are yet no standard protocols for its use in ovarian tissue cryopreservation (OTC). Published protocols diverse mainly in the supplementation of dimethyl sulfoxide (DMSO) to the vitrification medium and the use of an open or closed vitrification system. We investigated the vitality of ovarian tissue of transgender patients by Fluorescence Activated Cells Sorting (FACS) and histomorphological analyses using a DMSO-containing (P1) and a DMSO-free protocol (P2) in an open or closed vitrification setting. ResultsTwelve ovarian samples were donated from female-to-male transgender patients: 6 were vitrified according to protocol 1, the other 6 according to protocol 2. The amount of vital cells was 90.1% (P1) and 88.4% (P2) before vitrification. After vitrification and subsequent warming, vital cells were reduced to 82.9% (P1, p=0.093) and 72.4% (P2, p=0.019). When comparing the closed and the open systems, the decline in cell vitality from pre- to post-vitrification was significant only for the latter (p= 0.037). Histological examination reveals no significant differences with respect to degenerated follicles before or after vitrification. ConclusionThese results lend support to the hypothesis that a protocol containing DMSO results in a higher vitality of ovarian cells than a protocol that uses ethylene glycol as cryoprotective agent in vitrification. The use of an open vitrification system led to significant decline in the rate of vital cells. Trial registration: NCT03649087, retrospectively registered 28.08.2018